Vacuum generating device for sealing perishable products and method of use

ABSTRACT

A vacuum sealing device comprises a lid having a rigid rim with a lower opening for receiving a dish, an impermeable elastic membrane peripherally affixed to the rigid rim for sealing the dish, and a valve-less air evacuator formed between the elastic membrane and the dish rim. The valve-less evacuator allows air to flow out of the dish when the lid is being pressed and becomes closed when the lid is released to cause said lid to rebound to form a vacuum in the dish. The rigid rim prevents lid deformation when the lid is pressed, thus enabling the vacuum formation. To facilitate lid removal, the device has a valve-less vacuum releaser comprising a finger-receiving chamber and a section of the elastic membrane located above the chamber and connected to the rigid rim for releasing the vacuum in the dish. To prevent vacuum loss during storage in freezer or fridge, the elastic membrane is sufficiently thinned prior to being affixed to the rigid rim. In use, one places the lid on a dish, forces air out of the dish via the air evacuator between a section of the elastic membrane and the dish rim by pressing the lid, and releases the lid to cause the air evacuator to close and vacuum to form in the dish. To restore the device&#39;s capability to generate and maintain vacuum after numerous uses, the lid is exposed to a hot fluid having a temperature higher than 45° C. for a period of time.

FIELD OF THE INVENTION

This invention relates to a vacuum generating device for perishableproducts such as food, and is an improvement for the applicant's U.S.patent application Ser. No. 10/917,016.

BACKGROUND OF THE INVENTION

In commercial and home vacuum packaging, food is often placed in aplastic vacuum bag and the bag is subsequently evacuated and sealed by avacuum seal appliance such as FoodSaver® or Seal-a-Meal® sealer. Foraverage homes, such method is too labor intensive and complex for dailyfood storage. Moreover, the vacuum bag is normally disposed after oneuse, which is expensive and not environment friendly.

It is also known to place food in a vacuum container and evacuate thecontainer either by connecting the vacuum seal appliance to thecontainer lid via a vacuum tube as taught by FoodSaver® or Seal-a-Meal®sealer or by manually removing air via a check valve in the lid astaught by Wang in U.S. Pat. No. 6,557,462. Such vacuum containers aresusceptible to air leakage and plugging of the check valve and vacuumrelease valve in the lid by food. The check valve and vacuum releasevalve in the lid are also difficult to clean, which is not desirable forfood storage.

In the applicant's earlier invention disclosed in U.S. patentapplication Ser. No. 10/917,016, it was taught to seal food in existingkitchen containers with a vacuum lid comprising a rigid ring and anelastic membrane attached to the rigid ring.

The present invention is to provide a new vacuum storage device tosimplify the process of sealing food and other spoilable products and tosolve the problems with the vacuum storage devices described above.

SUMMARY OF THE INVENTION

The invention provides a vacuum sealing device having a lid for a dishor container adapted to receive the perishable product. The lidcomprises a rigid rim having a lower opening for receiving the dish, animpermeable elastic membrane whose peripheral section is connected oraffixed to the rigid rim for sealing to the rim of the dish, and avalve-less air evacuator formed between the elastic membrane and the rimof the dish. The rigid rim is made from a sufficiently rigid material toprevent it from being deformed when the lid on the dish is beingpressed. The valve-less air evacuator allows the air to flow out of thedish when the lid is being pressed and becomes closed when the lid isreleased to cause said lid to rebound and the space between said lid andcontainer to expand to form a vacuum in the dish. To facilitate theremoval of the lid, the device has a valve-less vacuum releasercomprising a finger-receiving chamber and a section of the elasticmembrane located above the finger-receiving chamber and connected to therigid rim for releasing the vacuum in the dish. The finger-receivingchamber is sufficiently large to allow a finger or finger-like member topass through and push said elastic seal member to release the vacuum inthe dish.

To prevent the sucking-in of the elastic membrane after microwave ovenheating and prevent potential crushing of the perishable product in thedish or damaging of the elastic membrane during said sucking-in, atleast one protruded section is provided on the elastic membrane or therim of the dish to cause the lid to tilt sufficiently on the dish. Toprevent the loss of vacuum in the dish during the storage of theperishable product in freezers and refrigerators, the elastic membraneis sufficiently thinned prior to being affixed to the rigid rim. Inanother embodiment of the invention, the elastic membrane may bereplaced by a rigid or semi-rigid center section and an elastic sealmember between the center section and the outer periphery of the rigidrim.

The present invention further provides a method for using the vacuumgenerating device by placing said lid on the dish containing aperishable product, forcing air out of the dish via an air evacuatorformed between a section of the elastic membrane and the rim of the dishby pressing the lid, and releasing the lid to allow the space betweensaid lid and dish to expand to form a vacuum therein. The method mayfurther comprise releasing the vacuum by placing a finger into thefinger-receiving chamber of the valve-less vacuum releaser and pushingthe elastic membrane and restoring the lid's capability to generate andmaintain vacuum in the dish after the lid is used one or more times byexposing the lid to a hot fluid having a temperature higher than 45° C.for a period of time.

DESCRIPTION OF THE DRAWING

The accompanying drawing illustrates diagrammatically non-limitativeembodiment of the invention, as follows:

FIG. 1 is a section view of a vacuum generating device having a vacuumlid on a dish before the vacuum is formed;

FIG. 1 a is a section view for the upper part of the device along lineA-A of FIG. 1;

FIG. 1 b is a section view of the device along line B-B of FIG. 1;

FIG. 1 c is a section view of the device of FIG. 1 when the lid is beingpressed by a hand or finger;

FIG. 1 d is a section view of the device of FIG. 1 c after releasing thelid;

FIG. 2 is a section view of a first modified version for the device ofFIG. 1;

FIG. 2 a is a section view for the upper part of the device along lineA-A of FIG. 2;

FIG. 2 b is a section view of the upper part of the device of FIG. 2when the lid tilts naturally on the dish;

FIG. 3 is a section view of a device having a vacuum lid on a dishbefore the vacuum is formed according to a second embodiment of theinvention;

FIG. 3 a is a section view of the upper part of the device of FIG. 3when the lid is being pressed by a hand or finger;

FIG. 3 b is a section view of the device of FIG. 3 a after releasing thelid;

FIG. 4 is a section view of a first modified version for the device ofFIG. 3, showing the modified vacuum lid and the upper part of the dishbefore the vacuum is formed;

FIG. 5 is a section view of a second modified version for the device ofFIG. 3;

FIG. 5 a is a section view for the upper part of the device along lineA-A of FIG. 5;

FIG. 5 b is a section view of the upper part of the device of FIG. 5when the lid tilts naturally on the dish;

FIG. 5 c is a section view of the device of FIG. 5 after the lid ispressed by a hand or finger and released;

FIG. 6 is a section view of a device having a vacuum lid on a dishbefore the vacuum is formed according to a third embodiment of theinvention;

FIG. 6 a is a section view of the device along line A-A of FIG. 6;

FIG. 6 b is a section view of the upper part of the device of FIG. 6when the lid is being pressed by a hand or finger;

FIG. 6 c is a section view of the device of FIG. 6 b after releasing thelid;

FIG. 7 is a section view of a device having a vacuum lid above a dishbefore a vacuum is formed according to a forth embodiment of theinvention;

FIG. 7 a is a section view of the device along line A-A of FIG. 7;

FIG. 7 b is a section view of the device along line B-B of FIG. 7;

FIG. 7 c is a section view of the device of FIG. 7 after the lid ispressed by a hand or finger and released;

FIG. 8 is a section view of a device having a vacuum lid on a dishbefore a vacuum is formed according to a fifth embodiment of theinvention;

FIG. 8 a is a section view of the device along line A-A of FIG. 8without showing the food in the dish;

FIG. 8 b is a section of the device of FIG. 8 when the lid is beingpressed by a hand or finger;

FIG. 8 c is a section view of the device of FIG. 8 b after releasing thelid;

FIG. 9 is a section view of the outer rigid rim, inner rim and themembrane of the lid of FIG. 8 before affixed between the upper and lowerrigid rims;

FIG. 9 a is a section view of the outer rigid rim, inner rim and themembrane that is being thinned about 30% to prevent loss of vacuum;

FIG. 9 b is a section view of the upper rigid rim, inner d rim and thethinned membrane after the thinned membrane is affixed between the outerand inner rims;

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

FIGS. 1-1 b show a vacuum generating device 1 having a vacuum lid 7 anda dish 2. The dish has a side wall 6, rim 21, bottom 4 and chamber 3 forreceiving food 5. Lid 7 has an elastic and air impermeable membrane 18having an outer seal section 28, a rigid rim 24 for adding strength tothe elastic membrane 18 and enabling the membrane to generate vacuum indish 2, and a valve-less air evacuator 16 formed between the sealsection 28 and the rim 21 of dish 2 for releasing the air in the dishwhen the lid is being pressed and for causing the seal section 28 toseal to the rim 21 to prevent air from entering the dish when the lid isreleased.

The rigid rim 24 comprises an outer rim 9 having a continuous channel 8around its peripheral and an inner rim 10 having an upper ridge 11receivable in channel 8 for sandwiching and affixing the periphery ofthe seal section 28 between the inner and outer rims. The outer rim 9further has an upper horizontal ring 20, an upper opening 19 to allowaccess to the elastic membrane 28, and a bottom-facing inner perimeter14. The inner rim further has a lower opening 22 to receive or surroundthe side wall 6 or rim 21 of the dish and a top-facing inner perimeter15 that fits to the bottom-facing inner perimeter 14 of the outer rim tocause the outer seal section 28 to conform to the contour or topographyof the bottom-facing inner perimeter 14 and top-facing inner perimeter15. The outer rim 9 comprises a rigid material such as metal, glass,ceramics or hard plastics (e.g. polycarbonate, polyester, polyacrylate,polystyrene, polypropylene or polyamide) to lend strength to the elasticmembrane 18 and to prevent the rigid rim 24 from deforming when theelastic membrane is pressed downward to the dish 2.

As shown in FIGS. 1, 1 a and 1 b, the valve-less air evacuator 16comprises a recessed section 14 a on the bottom-facing inner perimeter14 of the outer rim 9 and a protruded section 15 a on the bottom-facinginner perimeter 15 of the inner rim 10 receivable in the recessedsection 14 a to form a recessed section 17 on the seal section 28 of thelid. The recessed section 17 originates from the recessed section 14 aand protruded section 15 a of the rigid rim 24 and extends a distance Linto the seal section 28 of the elastic membrane 18 to form an opening27 between the recessed section 17 and the rim 21 of the dish 2. Theopening 27 stays partially open when the lid or elastic membrane ispressed downward by a finger or hand 25 (FIG. 1 c) to allow air to flowout of the dish. Upon release, the lid or elastic membrane tends torebound, thus causing the space between the lid and dish to expand and avacuum to form in the dish. The valve-less air evacuator is self closedto enable sufficient closing of the opening 27 to preserve the vacuum inthe dish for an extended period of time (FIG. 1 d).

To enable the sufficient closure of the valve-less air evacuator 16after the release of the lid or elastic membrane, it was found that theratio of the length (w) of the recessed section 14 a or protrudedsection 15 a along the inner perimeter of the rigid rim 24 to the height(h) of the recessed section 14 a or protruded section 15 a must belarger than 1. Preferably, the w/h ratio is larger than 5. For example,when h is 1 mm, w must be longer than 1 mm, preferably longer than 5 mm.A valve-less air evacuator with a w/h ratio smaller than 1 was found tocause the loss of the vacuum in dish 2 within days or even hours. It wasalso found that the thickness of the elastic membrane near the recessedsection 17 should be less than about 0.05 inches, preferably less than0.02 inches.

To allow the valve-less air evacuator to function, the maximum thicknessallowed for the elastic membrane 18 was found to be 0.25w or smaller.Long preservation (e.g. three to thirty weeks) of the vacuum in the dish2 was found to be achieved when the elastic membrane 18 in the vacuumlid was thinner than about 0.01 inches. The elastic membrane 18 may bemade from materials such as butyl rubber, nitrile rubber, ethyleneacrylic elastomers, ethylene propylene (or EPDM) rubber, natural rubber,polyurethane elastomers, styrene-containing block copolymer elastomers,Santoprene elastomer and polychroroprene elastomer.

When using vacuum device 1, one puts the perishable product 5 into thedish 2, places the lid 7 onto the dish (FIG. 1), and presses the lid orelastic membrane 18 by hand or finger 25 to evacuate the dish (FIG. 1 c)through the valve-less air evacuator 16. Although the valve-less airevacuator is reduced in size by the pressing of the lid, it is stillsufficiently large for air to flow out (FIGS. 1 and 1 c). By making thew/h ratio larger than 1 and preferably larger than 4, the valve-lessevacuator is able to close right after releasing the lid. After the lidis released or not pressed, the elasticity of the elastic membrane tendsto cause the lid 7 to move upwards to expand the space between the lidand the dish, thus causing a vacuum to form therein. The closing of theopenings 27 a and 2 b was found to be sufficient to preserve the vacuumup to weeks and even months.

It is appreciated that without the valve-less evacuator 16, it would bedifficult for air to flow out when the lid 7 is pressed and as resultthe dish 7 would have either very low vacuum or even no vacuum generatedtherein. The dish may be any container such as a bowl, platter,canister, can, drum, barrel, box, beaker, bottle or pot. The perishableproduct may be any product whose composition or physical property may bealtered by air or the pollutant or particles in air. Such productsinclude dry or wet foods, samples for analysis, chemicals, medicine,mechanical or electronic devices.

Because the device 1 of FIG. 1 enables a consumer to produce a vacuumseal by simply pressing the elastic membrane 18, it not only savesconsumers the money to buy expensive vacuum seal appliances but alsomake the vacuum sealing of food significantly faster and simpler. Moreimportantly, since device 1 evacuates air via valve-less air evacuator16 between the elastic membrane 18 and the rim 21 of the dish, it doesnot need any valves for extracting or removing air from the dish astaught in prior art vacuum devices by Saleri et al. in U.S. Pat. No.4,051,971, Romero et al. in U.S. Pat. No. 5,871,120, Breen in U.S. Pat.No. 6,148,875, Glaser in U.S. Pat. No. 6,194,011 and Wang in U.S. Pat.No. 6,557,462. Such air extraction or removal valves in the prior artvacuum devices comprise a valve opening and a movable valve member thatare susceptible to clogging by the solids in food and soup and toinsufficient closing of the valve opening by the movable valve member.The valve-less air evacuator, which replaces the air extraction valve inthe prior art, has no valve opening or movable valve member and isdirectly formed on the rim of the dish 2. As a result, the valve-lessair evacuator is cleaned every time when the dish is washed, and is thusmuch less susceptible to clogging or to insufficient closing than theprior art vacuum devices.

Moreover, unlike the prior art devices that contain difficult-to-cleanareas such as those in the valve openings or between the valve openingbase and valve member, the food in the present device 1 can only contactthe lower surface of the elastic membrane 18, which is easy to clean.The difficult-to-clean areas in the prior art devices may allow harmfulbacteria to grow and contaminate the food stored therein. Therefore, thepresent vacuum device 1 provides much more hygienic alternative to theprior art vacuum seal devices.

One of the problems discovered with the present invention of the vacuumdevice in FIG. 1 is that after heating the device containing food inmicrowave oven, the elastic membrane 18 of the lid 7 is sometimescompletely sucked into the dish 2 and crashed the food therein. In casethat the food contains sharp bones or shells, the elastic membrane wasfound to be weakened or even punctured by the food. The completesucking-in of the elastic membrane also made it very difficult to removethe lid from the dish 2 after the microwave heating. Such microwaveinduced sucking-in and crushed food problems were found to occur whenthe lid 7 was not promptly removed from the dish after the microwaveoven heating.

To resolve the microwave induced sucking-in and crushed food problems, aheat activated venting valve (not shown) was initially attached to theelastic membrane 18 of the lid of FIG. 1. The venting valve has a valveopening in communication with a punched opening (not shown) on theelastic membrane and a bi-metal plate that normally seals the valveopening. When the food in the device 1 was heated up, the bi-metal platedeformed and opens up the valve opening to vent the dish. The bi-metalplate remained in the deformed state to vent the dish after microwaveheating, thus preventing the elastic membrane from being sucked into thedish and from crashing the food. Unfortunately, the venting valve wasfrequently found to be clogged or to cause loss of vacuum due to leakagewhen the food contains soup or liquid.

An improved version for the lid 7 of FIG. 1 is provided (FIGS. 2, 2 aand 2 b) to resolve the microwave induced sucking-in and crushed foodproblems. In the improved lid 7, the valve-less air evacuator 16comprises a first protruded section 14 a on the bottom-facing innerperimeter 14 of the outer rim 9 and a first recessed section 15 a on thetop-facing inner perimeter 15 of the inner rim 10 receivable in thefirst protruded section 14 a to form a first protruded section 17 a onthe elastic membrane 18 and a second protruded section 14 b on thebottom-facing inner perimeter 14 and a second recessed section 15 a onthe top-facing inner perimeter 15 receivable in the second protrudedsection 14 a to form a second protruded section 17 a on the elasticmembrane (FIGS. 2 and 2 a). The protruded sections 17 a and 17 boriginate from the protruded sections 14 a and 14 b of the rigid rim 24,respectively and extends a distance L into the seal section 28 of theelastic membrane 18 to form openings 27 a and 27 b between the rim 21 ofthe dish 2 and the part of the seal section 28 that is lifted up by thetwo protruded sections 17 a and 17 b. Since the first and secondprotruded sections 17 a and 17 b on the seal section 28 of the elasticmembrane are located at the left side of the lid, the lid tends to tiltnaturally when placed on the dish 2 (FIG. 2 b). It was found that suchtilting of the lid on the dish prevented the elastic membrane from beingsucked into the dish and the food from being crashed after microwaveoven heating. It is believed that the tilting of the lid 7 on the dishmade the opening 27 b tall enough to prevent the elastic membrane frombeing sucked into the dish after microwave oven heating.

By adding more mass to the right side of the rigid rim 24, the tiltingof the lid 7 might be reversed to make the opening 27 a taller and theopening 27 b shorter. Such reversed tilting was discovered to be evenmore effective in preventing the elastic membrane 18 from being suckedin and the food 5 from being crushed. It was also found that it ispossible to enable the lid 7 to tilt on the dish when there is only oneprotruded section 17 a or 17 b formed on the elastic membrane as long asthe protruded section 17 a is sufficiently large, e.g. larger than 20%of the area of the elastic membrane 18. It was further discovered thatthe microwave sucking-in of the elastic membrane 18 and the crushing ofthe food 5 might be prevented without tilting the lid 7 if the height hfor the recessed section 14 a in the device 1 of FIG. 1 is larger than0.5 mm, preferably larger than 1 mm. However, the tilting of the lid 7was found to be several times more effective against the microwaveinduced sucking-in and crushed food problems than a deeper or tallerrecession 14 a. After all, the recession 14 a can not be too deep ortall to make the valve-less air evacuator 16 difficult to close. It wasthe noticed that when the height h of the recessed section 14 a becamelarger than 5 to 10 mm the valve-less evacuator became much lesscapable, if not incapable, to close to preserve the vacuum formed by thelid 7 in the dish.

When the dish 2 used in the device 1 of FIG. 1 or 2 is substantiallysmaller than the lid 7, it was found that to enable the lid to tilt(FIG. 2 b) or make the recessed section 14 a (FIG. 1) taller than 0.5 mmis not sufficient to resolve the microwave induced suck-in and crushedfood problems. To prevent the sucking-in and crushed food problems whena smaller diameter dish 2 is used, it was found that the length w of theprotruded or recessed section 14 a should be about 1/32, preferably ⅛,of the perimeter of the lid 7.

FIGS. 3, 3 a and 3 b provide a second improved version of the lid 7 ofFIG. 1 that has a sufficiently rigid center section 79 to prevent thesucking-in and crashed food problems after microwave oven heating. Theelastic membrane 18 adopts a ring shape. The inner and outer peripheriesof the ring-shaped elastic membrane are attached to the inner rim 10 andouter rim 9, respectively, to form a ring-shaped seal section 28 belowthe chamber 31 between the inner and outer rims. The valve-less airevacuator 16 comprises a portion 81 of the ring-shaped seal section 28.The elastic membrane in the portion 81 is thinner or easier to stretch,i.e. more stretchable, than the elastic membrane in the rest of thering-shaped seal section 28. A vacuum facilitating opening 29 is formedon the outer rim 9 for venting the chamber 31 to facilitating theformation of vacuum in the dish 2. Before the lid 7 is pressed, thevalve-less air evacuator 16 is closed and there is no gap between theportion 81 of the seal section 28 and the rim 21 of the dish (FIG. 3).When the lid is pressed by a hand or finger 25, the seal section 28 ispushed into the chamber 31 and the air pressure in the dish pushes thethinner or weaker elastic membrane at the portion 81 away from the rim21 of the dish to form the opening 27 to allow air to flow out of thedish (FIG. 3 a). The opening 29 lets air out of the chamber 31 toprevent any air pressure to form above the elastic membrane 18. Afterthe lid is released, the elastic membrane 18 tends to return to itsnatural position, thus causing the space between the lid and dish toexpand to form a vacuum and causing the elastic membrane in the portion81 to seal to the rim 21 of the dish (FIG. 3 b). Besides lowering thethickness or increasing the stretchability of the elastic film on theportion 81 to produce the valve-less air evacuator 16 when pressing thelid, it was found that providing a recessed or protruded portion on theseal section 28 like that in FIGS. 1 and 2 also produced the valve-lessair evacuator. In all cases, since elastic membrane 18 is confined bythe chamber 31 and the center section 79 of the lid is sufficientlyrigid, this improved lid 7 is not susceptible to the microwave inducedsucking-in and crushed food problems.

FIG. 4 provides a first modified version to the lid 7 of FIG. 3 that hasa sufficiently rigid center section 79 to prevent the microwave inducedsucking-in and crashed food problems after microwave oven heating. Inthis lid, the elastic membrane is replaced by a U-shaped seal gasket 32received in the annular chamber 31. The seal gasket comprises an annularbottom seal section 28, an annular empty chamber 82, and a valve-lessair evacuator 16 having an easy-to-compress neck section 34. An opening35 is formed on the side wall of the gasket 32 in communication with thevacuum facilitating opening 29 to facilitate the compression of the sealgasket. When the lid 7 is pressed, the neck section 34 allows an opening27 (not shown) to form between the rim 21 of dish 2 and the part of theseal section 28 located below neck section to allow air in the dish toexit. Since the center section 79 of the lid is sufficiently rigid, thisimproved lid 7 is also not susceptible to the microwave inducedsucking-in and crushed food problems.

FIGS. 5-5 c provide a second modified version to the lid 7 of FIG. 3that has a sufficiently rigid center section 79 to prevent thesucking-in and crashed food problems after microwave oven heating. Inthis alternative lid, the elastic membrane 18 is also replaced by aU-shaped seal gasket 32 received in the annular chamber 31. The sealgasket comprises an annular bottom seal section 28, an annular emptychamber 82, a opening 35 in communication with the vacuum facilitatingopening 29, and a valve-less air evacuator 16 comprising two protrudedsections 77, each having a length w and a height h, on the seal section28. The two protruded sections 77 sits on the rim 21 of the dish andcauses two openings 27 a and 27 b to form between the seal section 28and the rim 21 (FIGS. 5 and 5 a). The two protruded sections 77 are offcentered and located near the right side of the lid, causing the lid totilt naturally towards the left side on the dish 2 (FIG. 5 b). It wasfound that such tilting of the lid on the dish prevents the damage ofthe lid and the breakage or deformation of the dish after the dishcontaining wet food is heated in microwave oven.

When the lid 7 is pressed, the openings 27 a and 27 b become smaller butstill remains sufficiently large (not shown) to allow air to flow out ofthe dish. The air in the annular chamber 82 is also pressed out throughthe opening 35, the vacuum facilitating opening 29 and the openings 27 aand 27 b. By making the w/h ratio larger than 1 and preferably largerthan 5, the openings 27 a and 27 b are able to close right afterreleasing the lid. The elasticity of the gasket 3 tends to push the lid7 upwards to expand the space between the lid and the dish, thus causinga vacuum to form therein. The closing of the openings 27 a and 2 b wasfound to be sufficient to preserve the vacuum up to several days andeven weeks. Since the center section 79 of the lid is sufficientlyrigid, this improved lid 7 is not susceptible to the microwave inducedsucking-in and crushed food problems.

Another of the problems discovered with the present invention of thevacuum device 1 in FIG. 1 is that the lid 7 is difficult to be removedfrom the dish 2, especially when most of the air in the dish is removedor expelled. Such difficult-to-remove lid problem was found to beinconvenient to the users. It was also found to cause spill and messwhen one tries very hard to remove the lid from a dish that containssoup or other liquid. In case of hot soup, the spill might reach auser's hand and cause potential burning or hurting. FIGS. 6, 6 a, 6 band 6 c describe a valve-less vacuum releaser 43 for the device 1 toresolving this problem. The releaser 43 comprises a curved-out section94 on the rigid rim 24, a section of elastic membrane 48 affixed to thecurved-out section, and a finger receiving chamber 47 defined by thecurved-out section below the section of elastic membrane 48. The fingerreceiving chamber 47 is large enough to receive a finger or afinger-like member 41 (FIG. 6 c) to enable the finger to push theelastic membrane upward to generate an air passage for releasing thevacuum. The vacuum release by the finger 41 makes the removal of the lid7 from the dish spill-free and much less difficult.

The valve-less vacuum releaser further has a squeeze enabler 42 formedabove the section of elastic membrane 48. The squeeze enabler allows oneto place one finger above the enabler and another finger of the samehand below the elastic membrane to squeeze the membrane to release thevacuum in the dish. The enabler 42 can be a thin plate connected to therigid rim 24 as shown in FIG. 6 or one or more beams (not shown)connected to the rigid rim. It is important the squeeze enabler ispositioned sufficiently apart from the section of elastic membrane 48.The distance between the elastic membrane and the enabler should be morethan about 2 mm, and is preferably more than 4 mm or 0.16 inches.

The vacuum relief valves in the vacuum food containers taught by theprior art and products such as the FoodSaver® or Seal-a-Meal® vacuumcanisters have a small valve opening and a seal member that seals thevalve opening during food storage and is manually moved away from thevalve opening to release the vacuum prior to removing the lid. Similarto the air extraction valve used in the prior art products, such vacuumrelief valves are susceptible to clogging, insufficient closing andbacteria growth problems. The valve-less vacuum releaser 43 has no suchvalve openings or seal member, and is thus immune to such problemsduring everyday home uses. It is appreciated that for the very lowvacuum that forms in conventional sealed containers when refrigerated orin containers sealed by Amco or Progressive's silicone lids, the lid maybe removed by just pushing up the rim or periphery of the lid. It isalso appreciated that the valve-less vacuum releaser 43 may used for thelid for the vacuum food canisters and sealed containers.

During use, it was found that a much deeper vacuum was formed in thedish if the curved-out section 94 of the releaser is lifted or pushedupward slightly by a hand 44 while the elastic membrane 18 is beingpressed into the dish by a hand or finger 25 (FIG. 6 b). It isappreciated that the valve-less vacuum releaser 43 can also be formed onthe vacuum lid 7 of the device 1 described in FIGS. 3 to 5. Thecurved-out section 94 of the releaser 43 is formed on the out rim 9 ofthe annular chamber 31 and the ring-shaped or annular seal section 28 isextended into the curved-out section 94 to form an elastic section 48affixed to the curved-out section 94 (not shown).

FIGS. 7, 7 a, 7 b and 7 c describe a first modified version of thevalve-less vacuum releaser 43 for the vacuum lid 7. The device 1 has arectangular dish 2 and a rectangular vacuum lid 7 having a rectangularelastic membrane 18 affixed to the rigid rim 28 of the lid and twovalve-less vacuum releasers 43, one on the left and the other on theright side of the lid. The lower opening 22 of the lid 7 is dimensionedto receive the rim 21 and the two handles 49 of the dish 2. Eachvalve-less vacuum releaser 43 comprises a first finger-receiving chamber47 b in a handle 49 of the dish 2, a section of elastic membrane 48above the first finger-receiving chamber 47 b, a second finger-receivingchamber 47 a below the section of elastic membrane 48 in the lid 7, andsqueeze enabling plate 42. The squeeze plate 42 is located apredetermined distance above the upper horizontal ring 20 formed on theouter rim 9 (FIGS. 7 and 7 b). The first finger-receiving chamber 47 bhas an inner chamber 52 and an outer opening 51 (FIG. 7 a) sufficientlylarge to allow a finger 41 to pass through to reach the secondfinger-receiving chamber 47 a and the section of elastic membrane 48 topush the elastic membrane to release the vacuum in the dish (FIG. 7 c).

FIGS. 8, 8 a, 8 b and 8 c describe a second modified version of thevalve-less vacuum releaser 43 for a round vacuum lid 7 comprising around elastic membrane 18 with its peripheral section 28 affixed to therigid rim 24 similar to that described in FIG. 1. The valve-less vacuumreleaser 43 comprises a finger-receiving chamber 47 formed by curving orrecessing the side wall 6 of the dish 2 and the section of elasticmembrane 48 above the finger receiving chamber (FIGS. 8 and 8 a). Thechamber 47 is sufficiently large to receive a finger or finger-likemember 41 to allow the finger to push the section of elastic membrane 48to release the vacuum in the dish (FIG. 8 c). In this preferredembodiment, the part of the upper horizontal ring 20 located apredetermined distance above the section of elastic membrane 48 couldfunction as the squeeze enabler 43 to facilitate the release of thevacuum in the dish 2.

A protruded section 57 is provided on the front part and anotherprotruded section 57 on the back part of the rim 21 of the dish 2 toform openings 27 a on the left and openings 27 b on the right side ofthe protruded sections 57. Both the front and back protruded sections 57are positioned near the right part of the dish to cause the lid 7 totilt towards the left side to make openings 27 b significantly largerthan openings 27 a for preventing the microwave induced sucking-in andcrushed food problems discussed earlier for the device 1 of FIG. 1. Theopenings 27 a and 27 b also functions as the valve-less air evacuator 16that enables air in the dish to be evacuated when a hand or finger 25presses the elastic membrane 18 of the lid into the dish (FIG. 8 b) andenable sufficient closing of the openings 27 a and 27 b after releasingthe lid to preserve the vacuum formed in the dish 2 (FIG. 8 c).

Another of the problems discovered with the present invention of thevacuum device 1 in FIG. 1 is the loss of vacuum in the dish 2 after anextended period of storage in freezer and refrigerator. Such loss ofvacuum was initially thought due to the presence of the valve-less airevacuator 16. Later studies found that the vacuum disappeared in severaldays and sometimes in half a day even if the valve-less air evacuatorwas intentionally removed from the device 1. Such vacuum loss in thedish was found to occur with various elastic membranes such as butylrubber, ethylene acrylic elastomers, ethylene propylene (or EPDM)rubber, polyurethane elastomers and natural rubber membranes. Althoughthe reason for such vacuum loss was still not understood, it wasdiscovered, quite by accident, that if the elastic membrane 18 wasthinned about 12% compared to the membrane's original thickness, theloss of vacuum in the dish 2 was prevented or at least significantlyreduced. In several long-term storage tests, it was found that thevacuum lid 7 comprising an elastic membrane 18 that was thinned about12% could maintain the vacuum in the dish for six months to a year. Incomparable tests with the same elastic membrane but with the membranenot thinned in the vacuum lid 7, the vacuumed in the dish 2 lasted onlyseveral days.

FIGS. 9 a-c shows the thinning process for the elastic membrane 18before affixing it to the rigid rim 24. Before the thinning, the elasticmembrane 18 was thick and its peripheral edge was clamped by clamp 72(FIG. 9). The elastic membrane was placed between the outer rigid rim 9and inner rim 10. FIG. 9 b shows the elastic membrane 18 after themembrane was thinned about 25% by stretching the elastic membrane 18with the clamp 72. FIG. 9 c shows the vacuum lid 7 with the thinnedelastic membrane sandwiched between the inner and outer rims 9 an 10.The inner rim 10 is prevented from separating from the outer rim 9 bythe annular channel 11 in the outer rim 9 and the ridge 8 on the innerrim 10, where the thickness of the ridge 8 plus two times of thethickness of the thinned elastic membrane is larger than the gap forannular channel 11. To prevent the vacuum loss in the dish 2 when storedin refrigerator or freezer, the thinning of the elastic membrane 18 inthe vacuum lid should be about 3% or more depending on the nature andoriginal thickness of the elastic membrane, and be preferably more than8% prior to affixing the membrane to the rigid rim 24.

It was found that after the lid 7 was used to generate and maintainvacuum in the container one or more times, the lid gradually lost itscapability to generate and maintain sufficient vacuum for the perishableproduct. It was further found that the lid's capability to generate andmaintain vacuum could be restored, at least partially, by exposing thelid to a hot fluid such as hot water having a temperature higher than45° C. for about 10 seconds to several minutes. Higher hot fluidtemperature up to 95° C. and longer exposing time was found to restorethe lid's vacuum generating and maintaining capability in some casesmore effectively.

It was discovered that although a vacuum lid 7 with its elastic membrane18 thinned as much as 10% could maintain the vacuum in the dish 2 forseveral weeks to months in freezer or refrigerator, the same vacuum lidcould not maintain the vacuum in the dish for more than one or two daysin the same refrigerator or freezer after the dish covered by the vacuumlid was heated in microwave oven once or twice. It is believed that themicrowave caused certain structural or compositional changes in thethinned elastic membrane 8 that is detrimental to the preservation ofthe vacuum between the dish 2 and the vacuum lid 7. Various protectionsfor the elastic membrane, such as covering the elastic membrane by aplastic wrap films and even perforated aluminum foils, were found noteffective in preventing such microwave-induced vacuum loss in the dish2. It was discovered that the vacuum loss, however, could be preventedby thinning the elastic membrane more than 15%, preferably more than 25%before affixing the elastic membrane to the rigid rim 24.

The scope of the invention is obviously not restricted or limited to theembodiments described by way of examples and depicted in the drawings,there being numerous changes, modifications, additions, and applicationsthereof imaginable within the purview of the claims.

1. A vacuum generating device for sealing a perishable productcomprising: a lid for a container adapted to receive the perishableproduct, said lid comprising a center section substantially impermeableto air to prevent air from permeating through into the container, arigid rim located around said center section for receiving orsurrounding the container, said rigid rim comprising a sufficientlyrigid material to prevent it from being substantially deformed when saidlid on the container is being pressed, and an elastic seal memberconnected or affixed to said rigid rim for forming an airtight seal tothe rim of the container; a valve-less air evacuator formed between asection of said seal member and the rim of the container, saidvalve-less air evacuator allowing the air to flow out of the containerwhen said lid is being pressed and becoming closed when said lid isreleased to cause said lid to rebound and the space between said lid andcontainer to expand to form a vacuum in the container; and whereby inuse, said lid is pressed to cause the air to flow out of the containervia said valve-less air evacuator and is subsequently released to formsaid vacuum to cause the closing of said valve-less air evacuator,thereby preserving said vacuum for the perishable product in thecontainer for an extended period of time.
 2. A vacuum generating deviceas defined in claim 1 wherein said valve-less air evacuator comprises aportion of said seal member that is sufficiently more deformable thanthe rest of said seal member to enable an air passage to form betweensaid portion of said seal member and the rim of the container as saidlid is being pressed and that is sufficiently elastic to stamp out saidair passage when said lid is released to form said vacuum.
 3. A vacuumgenerating device as defined in claim 1 wherein said seal membercomprises an elastic membrane attached or affixed to said rigid rim,said elastic membrane having a lower surface for sealing to the rim ofthe container and an upper surface.
 4. A vacuum generating device asdefined in claim 3 wherein said elastic membrane comprises a sectionhaving a lower tension force than the rest of said elastic membrane toform said valve-less air evacuator between said lower tension section ofsaid elastic membrane and the rim of the container.
 5. A vacuumgenerating device as defined in claim 1 wherein said valve-less airevacuator comprises at least one of a protruded section and a recessedsection for said seal member to form at least one opening between saidseal member and the rim of the container to allow air to flow out of thecontainer as said lid is being pressed, said seal member beingsufficiently elastic and flexible to stamp out said at least one openingupon release of the lid to form said vacuum.
 6. A vacuum generatingdevice as defined in claim 5 wherein the width (w) to height (h) ratiow/h of said at least one of a protruded section and a recessed sectionis larger than
 4. 7. A vacuum generating device as defined in claim 6wherein the maximum thickness of said seal member allowed for saidvalve-less air evacuator to work is 0.25 times of the width (w) of saidat least one of a protruded section and a recessed section.
 8. A vacuumgenerating device as defined in claim 5 wherein said seal member andcenter section of said lid comprise an elastic membrane, the peripheryof said elastic membrane being attached or affixed to said rigid rim. 9.A vacuum generating device as defined in claim 8 wherein said at leastone of a protruded section and a recessed section is formed by providingat least one of a protrusion and a recession along the inner perimeterof said rigid rim and by connecting or affixing said elastic membrane tosaid rigid rim in such a way that the outer part of said elasticmembrane conforms to the contour of said inner perimeter of said rigidrim.
 10. A vacuum generating device as defined in claim 8 wherein saidrigid rim has a first rim having a recession along its inner perimeterand a second rim having a protrusion receivable in said recession ofsaid first rim, said first and second rims being adapted to sandwich andaffix the peripheral part of said elastic membrane between said firstand second rims to form said at least one of a protruded section and arecessed section.
 11. A vacuum generating device as defined in claim 8wherein said at least one of a protruded section and a recessed sectionis sufficiently wide and high to make said at least one opening betweensaid elastic membrane and the rim of the container sufficiently large toprevent the sucking-in of said elastic membrane after microwave ovenheating, thereby preventing potential crushing of the perishable productin the container or damaging of the elastic membrane during saidsucking-in.
 12. A vacuum generating device as defined in claim 1 whereinsaid center section and seal member of said lid comprise an elasticmembrane and, wherein said valve-less air evacuator comprises asufficiently large protruded or recessed section for said elasticmembrane to form a sufficiently large air passage between thecontainer's rim and said elastic membrane to prevent the sucking-in ofsaid elastic membrane after microwave oven heating, thereby preventingpotential crushing of the perishable product in the container ordamaging of the elastic membrane by said sucking-in.
 13. A vacuumgenerating device as defined in claim 1 wherein said center section andseal member of said lid comprise an elastic membrane and, wherein saidvalve-less air evacuator comprises at least one protruded sectionadapted to cause said lid to tilt sufficiently on said container toprevent the sucking-in of said elastic membrane after microwave ovenheating, thereby preventing potential crushing of the perishable productin the container or damaging of the elastic membrane during saidsucking-in.
 14. A vacuum generating device as defined in claim 1 whereinat least said seal member of said lid comprises an elastic membrane,said elastic membrane being substantially thinned prior to beingattached or affixed to said rigid rim to prevent the loss of vacuum inthe container during an extended period of storage.
 15. A vacuumgenerating device as defined in claim 1 further comprising a valve-lessvacuum releaser for releasing the vacuum in the container, therebyallowing the removal of said lid, said port being sufficiently large toallow a finger or finger-like member to reach and push said seal memberaway from the rim of the container to produce a passage for air to enterthe container.
 16. A vacuum generating device for sealing a perishableproduct comprising: a lid for a container adapted to receive theperishable product, said lid comprising an elastic seal member forforming an airtight seal to the rim of the container, said elastic sealmember being substantially impermeable to air to prevent air frompermeating through into the container, and a rigid rim connected to saidelastic seal member for receiving or surrounding the rim of thecontainer, said rigid rim comprising a sufficiently rigid material forpreventing said rigid rim from being substantially deformed when saidlid is pressed to deform said elastic seal member to force air out ofthe container and for forming and preserving vacuum in the containerafter said lid is released; a valve-less vacuum releaser for releasingthe vacuum in the container to facilitate the removal of said lid, saidvalve-less vacuum releaser comprising a finger-receiving chamber and asection of said elastic seal member located above said finger-receivingchamber and connected to said rigid rim, said finger-receiving chamberbeing sufficiently large to allow a finger or finger-like member to passthrough and push said elastic seal member to release the vacuum in thecontainer; and whereby in use, to form a vacuum in the container onepresses said lid to force the air out of the container and subsequentlyreleases said lid, and to open the container one places a finger orfinger-like member into said finger-receiving chamber and pushes saidelastic seal member to release said vacuum in the container.
 17. Avacuum generating device as defined in claim 16 wherein valve-lessvacuum releaser further comprises a squeeze-enabler connected to saidrigid rim and located a predetermined distance above said section ofsaid elastic seal member, thereby enabling one to place a finger on saidsqueeze-enabler and another finger in said finger-receiving chamberunderneath said elastic membrane and to squeeze to release the vacuum inthe container.
 18. A vacuum generating device as defined in claim 16wherein valve-less vacuum releaser further comprises a curved-outsection on said rigid rim for defining said finger-receiving chamberbelow said section of said elastic seal member.
 19. A vacuum generatingdevice as defined in claim 16 wherein said finger-receiving chamber isformed by curving inward or recessing a section of the side wall of thecontainer.
 20. A vacuum generating device as defined in claim 16 whereinsaid finger-receiving chamber comprises a first finger-receiving chamberformed in a handle connected to the side wall of said container and asecond finger-receiving chamber formed within said lid and located belowsaid section of said elastic seal member.
 21. A vacuum generating deviceas defined in claim 16 wherein said elastic seal member comprises anelastic membrane having a peripheral section affixed to said rigid rim.22. A vacuum generating device for sealing a perishable productcomprising: a lid for a container adapted to receive a perishableproduct, said lid comprising an elastic membrane for sealing to the rimof the container, said elastic membrane being substantially impermeableto air to prevent air from permeating through into the container, and arigid rim connected to the peripheral section of said elastic membrane,said rigid rim comprising a sufficiently rigid material to prevent itfrom being substantially deformed when said elastic membrane is pressedinto the container to force the air out of the container; and whereinsaid elastic membrane is sufficiently thinned prior to being connectedor affixed to said rigid rim to prevent the loss of vacuum in thecontainer during the storage of said perishable product.
 23. A vacuumgenerating device as defined in claim 22 wherein said elastic membraneis thinned at least 4% prior to being connected or affixed to said rigidrim to prevent the loss of vacuum.
 24. A vacuum generating device asdefined in claim 22 wherein said elastic membrane is thinned at least15% to prevent said lid from losing its capability in preserving thevacuum in the container after said lid is used to cover a container toheat the perishable product in microwave oven at least once.
 25. Amethod for using a vacuum generating device to seal a perishable productcomprising a lid for a container adapted to receive the perishableproduct, said lid comprising a center section substantially impermeableto air to prevent air from permeating through into the container, arigid rim located around said center section for surrounding thecontainer, said rigid rim comprising a sufficiently rigid material toprevent said rigid rim from being substantially deformed when said lidon the container is pressed, an elastic seal member connected to saidrigid rim for sealing to the rim of the container, and an air evacuatorformed between a section of said seal member and the rim of thecontainer, said method comprising: placing said lid on the containercontaining a perishable product; forcing air out of the container viasaid air evacuator between said section of said elastic seal member andthe rim of the container by pressing said lid on the container; andreleasing said lid to allow the space between said lid and container toexpand to form a vacuum therein.
 26. A method as defined in claim 25wherein said device further comprises a valve-less vacuum releaserhaving a finger-receiving chamber and a section of said elastic sealmember located above said chamber, said method further comprising a stepof placing a finger or finger-like member into said finger-receivingchamber and pushing said elastic seal member to release the vacuum inthe container.
 27. A method as defined in claim 25 further comprising astep of lifting a portion of said rigid rim slightly during said step offorcing air out of the container and a step of letting said portion ofsaid rigid rim down prior to said step of releasing said lid, therebyproducing a deeper vacuum in said container.
 28. A method as defined inclaim 25 wherein said seal member comprise an elastic membrane having aperipheral section affixed to said rigid rim, said method furthercomprising a step of exposing said lid to a hot fluid having atemperature higher than 45° C. for a period of time to restore saidlid's capability to generate and maintain vacuum in the container aftersaid lid is used one or more times.